Various prosthetic dentures have been produced by setting groups of individual teeth in hard base structures and final impression fitting of such hard base structures have been generally performed by inserting the hard base structure into the mouth of a patient with various impression taking materials and subsequently the impressions are utilized for producing a suitable recess adapted to fit an edentulus ridge of a patient from which the impression is taken.
Heretofore, impressions of a toothless gum area have been made and it has been common practice to produce hard base dentures in accordance with such impressions; however, due to the mass of material involved in producing a hard base denture, it has been difficult to allow such hard base material to cure in a person's mouth in an impression taking position, and thus costly and complex methods have always been resorted to in the production of a prosthetic denture. Many of the plastic materials which are hardenable are utilized for producing a prosthetic gum structure adjacent to prosthetic teeth and due to the structural mass requirements in the amount of plastic material to be cured in connection with the prosthetic teeth is such as to cause discomfort of a patient and thereby preventing the complete impression taking and curing of the hard base structure in a patient's mouth.
Additionally, the prior art has employed elastomeric material which is curable at low temperature in person's mouth for taking impressions therein, and many such materials are only intimately bondable to a like material but not readily bondable to a hard base plastic material such as an acrylic material or the like. Dentures produced in this manner have encountered functional difficulties hereinbefore described, in that the food particles are collected between the elastomeric material and the prosthetic teeth during mastication of food in the mouth of a person wearing such prior art prosthetic dentures.
Some prior art prosthetic dentures have been produced with hard rigid palate portions adapted to be placed adjacent the palatal vault of a person's mouth and due to the various configurations of person's mouths, these hard palate portions have been unsatisfactory since in many cases relatively thick liners have caused the hard palate area to become quite thick, which tends to create speech as well as mastication problems.
In addition to the foregoing prior art dental practice, many approaches have been made to the provision of a modular artificial denture which may be readily and easily fitted to a variety of patients and which may be satisfactory both as to occlusion and as to overall comfort.
Even though various modular artificial dentures have been produced and even though they have been centrically related as maxillary and mandibular sets, the cusp areas of the related maxillary and mandibular units have been unnatural to the particular patient and have caused occlusion excursions which have created temporo mandibular joint syndromes or spasms of the muscles of mastication. This problem has rendered the art of modular prosthetic dentures somewhat lacking in practical application. Any set of dentures, including a maxillary denture and a mandibular denture which is adapted to fit a variety of patients, will without exception have cusp occlusion areas which will be unnatural to some patients and eventually cause temporo mandibular joint syndrome.
Additionally, the mandibular units of prior art modular dentures have lacked proper support so as to remain in place for proper occlusion and for comfortable and reliable use.